This Is Going To Be Fun
by Erenem
Summary: What is if someone else was also there that night at the pool? Someone we thought we all knew?


She shifted her weight minutely, careful not to make a noise. Her team had been in place in the gallery for almost an hour. As she stretched out her cramped muscles, she admired how the light from the changing areas glinted off the water, giving the pool an otherworldly glow in the mostly darkened room, making it the center of attention. The stage was perfectly set.

Her thoughts drifted to the man they were waiting for, this Sherlock Holmes. She did not understand why her boss had become so fixated on him, when Holmes should obviously be beneath his notice. Holmes would never have figured out any of these "cases" if her boss hadn't pointed him in the right direction. Regardless, Jim was obsessed, and he did so love watching Holmes dance.

Adding to the list of things she did not understand: why Jim was so excited that Holmes had picked this pool for their show down. It seemed an odd place for such a scene; but then, Jim certainly didn't tell her everything.

She heard the door below her open and close. She gave herself a mental shake.

_Get your head in the game, Mary. It's show time!_

A tall, lanky man finally came into view right below her. He stopped, then gazed around at the darkened gallery above him. _Smart man,_ she grudgingly thought. Of course, he would never be able to see her or any of her team – they were all too well trained.

"Brought you a little getting-to-know-you present." Holmes sounded almost excited, like he was looking forward to this confrontation. "Oh, that's what it's all been for, hasn't it? All your little puzzles; making me dance – all to distract me from _this."_ Holmes continued looking around, turning his back to the pool. At that moment, she heard Jim's voice over her com. A shiver of anticipation ran down her spine.

_This is going to be fun._

The sound of another door opening echoed in the room, and the little soldier stepped out. Holmes turned his head towards the noise, and then his whole body froze.

_Oh, what I wouldn't give to see the look on his face right now,_ thought Mary with a mixture of disappointment and glee.

Since she couldn't see Holmes' face, she focused on the other man instead. Jim hadn't told her much about John Watson other than he had once been a soldier and was now Holmes' pet. He stood still, back straight, parroting Jim's words back to Holmes. As she watched, she noticed Watson's eyes blinking furiously. S.O.S. Mary was impressed.

_Oh he's good. Very good._

"John." The name came out as a gasp, almost like a plea_._ Mary didn't have to see Holmes' face to understand the emotion – the betrayal and heartbreak – behind that one word. That one word spoke volumes.

_How could he possibly think that this little soldier is Jim? _

" Bet you never saw _this_ coming," John parroted.

_And that's my cue._

Watson pulled his hands out of his pockets to open his coat, displaying the vest of explosives he was wearing underneath as he said nonsense words. Mary aimed her sniper rifle and turned on the laser sight at the same time. The little red dot stood out blood red on the vest, right above his heart.

Holmes finally started walking towards Watson, but he searched all around the room instead of looking at his pet. "Stop it," Holmes said, as he turned around to look up at the gallery again, his face a display of fear and bewilderment. Amusement and something like triumph flowed through Mary's body when she saw that look on Holmes' face.

_Ha! It's all fun and games until your pet gets kidnapped and has a bomb strapped to him. Jim really caught you off guard with this, didn't he? _

Jim kept speaking through Watson, something about someone named Carl Powers and stopping John Watson's heart. Mary wasn't really paying attention to the actual words. She was much too entertained by the scene unfolding in front of her. Watson seemed quietly resigned and oddly calm, given that he was covered in explosives with a sniper rifle aimed right at his chest. He only flinched when he had to talk about Jim stopping his heart. Holmes, on the other hand, was on the edge of a breakdown as he continued walking to Watson, his fidgety left hand and his breathing giving away the emotional turmoil he boiling underneath his seemingly cool exterior. Mary wondered if Holmes knew how much he was giving away right now. Maybe the untrained eye wouldn't see his emotional tells, but both she and Jim were far from untrained.

Sherlock finally snapped, "Who _are_ you?"

On the other side of the pool, another door could be heard opening. A voice called out in sing song, "I gave you my number. I thought you might call."

And then the man himself stepped into view. Jim Moriarty, the most intelligent and sexy man she had ever met. Another shiver ran down Mary's spine, but this one was a shiver of desire.

As the men did their introductions, Mary let her thoughts wander a bit, imagining Jim's hands running all over her just earlier that day. He was almost always nearly insatiable after the high he got whilst playing his little games.

_Nearly_.

Mary owed Jim her life. She had been so dreadfully bored working all those jobs for the CIA. Sure, setting up and following through with a kill was certainly enjoyable, but she never got to kill anyone worthwhile or challenging. Always just boring people that the US government felt _might_ become a threat one day.

_Boring._

Then on an assignment in Prague, she had met _him_: James Moriarty. She still sometimes wondered what about her had caught his attention. She had been instantly attracted to him, with his lilting accent, gorgeous face, and waves of danger that radiated off of him. After a whirlwind weekend of amazing sex and little else, Jim had explained who he was and what he did, and asked if she wanted to join him. She knew instantly that if she refused she would be found dead somewhere – or never found at all – but refusing never really crossed her mind. Jim was offering her a world of excitement and danger – how could she possibly refuse? And so, after that fateful weekend in Prague, Allison Archer, CIA agent, disappeared, considered missing in action, and Mary Moran was born. James Moriarty saved her from a life of monotony, and for that she would follow him to the ends of the earth.

The sound of a gun cocking pulled her sharply back to the scene before her. Jim was still relaxed, so she kept her rifle pointed at Watson and began paying attention to the conversation taking place below her – actually, the _flirting_ taking place below her. A tiny sliver of jealousy dropped into her stomach.

_What was it about this guy that has Jim so interested? Why is he so captivated by this seemingly ordinary person?_

Mary could not begin to understand what it was that attracted Jim to Holmes. It annoyed her so much that when Jim flashed his devastating smile – the one she thought he reserved for her – at Holmes of all people, her aim slipped a bit, causing the laser to jump all over Watson's chest.

_Get your shit together, Mary_, she chided herself. _You know he's just playing with Holmes, trying to rile him up._ Because that _was_ what Jim was doing, wasn't it?

During Jim and Holmes' conversation, Watson's calm façade seemed to be slipping. He closed his eyes and shook his head every now and then. A look of disgust briefly crossed his face as Jim talked about the game he and Holmes had been playing. Or maybe it was a brief hint of jealousy.

_Could Watson be feeling what I am feeling as well?_ She supposed there were parallels between them. Both of them were soldiers, of a sort; both of them were loyal companions to their crazy geniuses.

"You all right?" Holmes finally asked Watson. Watson, still following orders from Jim, stayed still and quiet, trying to talk to Holmes with his eyes.

_Such a perfect little soldier. _

Jim walked over and leaned in towards Watson, telling him that he could talk now. Mary had a good aim on Watson, and was an ace shot besides, but she moved her aim over to the right and away from Jim, just to be safe.

Jim then stepped forward to take something that Holmes was offering him – a flash drive by the looks of it. With Jim so close to Holmes now, Mary focused more on Jim than Watson, to watch for any threats from Holmes. With her attention thus averted, she did not observe any of Watson's tells that he was about to attack until it was too late. Apparently she wasn't the only one surprised, as Holmes took a step back from the struggling pair.

_Sneaky little soldier. _

With her heartbeat pounding in her ears, she focused on Jim, willing him to give a signal to end this all. With a sigh, however, she relaxed. Jim's face was alight with an evil sort of joy as he laughed and smiled as though it were Christmas – which for them, it was.

_Watson's just given up the game_. _He's just shown he's willing to sacrifice himself for Holmes._ _We can now use them both against each other. This really is so much fun._

"Isn't he sweet? I can see why you like having him around. But then people do get so sentimental about their pets." Watson struggled with Jim, causing Mary to shift her aim away from Jim and back onto Watson, even if it is only on his arm. Jim scowls back at Watson, saying "They're so touchingly loyal. But, _oops!" _

Jim's eyes locked on Mary's for the briefest of moments and she nodded back at him. Mary signaled to her man on the other side of the pool, who aimed and turned on his laser just as Jim was telling Watson that he had rather shown his hand. The fear in Watson's eyes was easy to read even from as far away as she was. Watson dropped Jim immediately, backing away, raising his hands, and looking resigned, beaten.

_It's good to know when you've been beaten._

Jim smoothed down his suit and scolded Holmes. He then proceeded to tell Sherlock to back off, though Mary thought that this was a bit odd seeing as Holmes only really knew about Jim because Jim wanted him to. That was the whole point of this "game" they had been playing, wasn't it?

"I will burn you. I will burn the _heart_ out of you," Jim warned.

"I have been reliably informed that I don't have one."

Mary nearly laughed out loud at that. Was Holmes serious? Did he not realize that they had all seen the emotion written all over his face, all over his body when he realized that Watson was in mortal danger? Did he not realize that it was somewhat symbolic that she had her rifle pointed at Watson's heart, when the easy kill would be to aim at his head?

_Oh, this is just too easy. Playing with the both of them would be so much fun._

"Well, I'd better be off." Mary sighed a little in relief. As much as she wanted to play with Holmes and Watson, she would prefer for it to be somewhere where everyone didn't have guns pointed at them. As much as she loved brute force, there was something so much more elegant and sexy about psychological warfare.

"It was so nice to have had a proper chat."

"What if I was to shoot you now – right now?" Holmes lifted the gun higher. Mary watched Holmes closely.

"Well then, you'd get to cherish the look of surprise upon my face. Because I would be surprised, Sherlock, really I would. And just a teensy bit disappointed. And of course, you wouldn't get to cherish it for very long."

_That's for sure. I'd put a bullet in his head before Jim ever hit the ground._

"Ciao, Sherlock Holmes."

Jim left through the same door that Watson had come in earlier while Holmes kept his gun trained on Jim's retreating figure. Once Jim was through the door, Mary relaxed slightly and turned off the laser on her rifle, though she kept the gun aimed at Watson. Mary planned to keep them in her sights until they had actually left the building.

Holmes eventually looked at Watson, holding his gaze for a second before dropping the gun on the ground and going to his knees in front of Watson. Watson seemed to sag, barely able to hold up his own weight anymore. As Mary watched, Holmes began frantically taking off the vest as Watson's head fell back.

_Oh. My. God. This just keeps getting better and better. Who knew I was going to be getting quite a show tonight!_

Holmes finally got the vest off Watson and threw it as far away from him as he could. Without Holmes there to steady him, Watson collapsed forward and squatted down as all the adrenaline left his body.

_He is certainly made of stronger stuff than he seems. You would have never known he was that scared when Jim was still in the room._

As Mary grudgingly admitted even more respect for Watson, Holmes bent down and picked back up his gun, distractedly scratching his head with it as he stammered out a thanks to Watson for offering to save his life. He was almost acting as if-

_Hold on. Please don't tell me that he had no idea that Watson would risk his life for him. Can these two idiots really not see how much they care for each other? _

"I'm glad no one saw that," Watson deflected. "You, ripping my clothes off in a darkened swimming pool. People might talk."

Mary nearly snorted. She couldn't believe that Watson was making a joke right after he could have possibly been blown to bits. She couldn't help but think that John Watson had a sense of humor that matched hers.

"People do little else." Mary nearly snorted again.

_Are they always like this? Laughing and joking after near death experiences? Do they have any idea how lucky they are to have each other?_

Mary shook her head at these two idiots – idiots she would most likely have to kill someday – and was starting to wonder when they would leave so she could get her team out of here, when she heard Jim's voice in her com, "I'm coming back, I want the full cavalry this time."

_What the fuck? What is he playing at? We were this close to all getting out of here alive._

As adrenaline raced through Mary's system, she wondered what was going on in Jim's mind. There were times when Jim would slip away from her and into some dark place in his mind. It happened more than she would ever like to admit, and it always bothered her that she couldn't pull him out. It also scared her a little bit, because she could handle dark – she _was_ dark – and yet that dark place in Jim's mind was something she couldn't begin to understand.

_What changed his mind about leaving?_

Mary nodded her head, and her team all turned on their lasers, so that Holmes and Watson were covered in red spots, just as Jim entered the room from a door farther away.

"Sorry boys, I'm _so_ changeable!"

_You can fucking say that again. _

Mary was not happy about this change of events. Not one bit. Neither were Holmes and Watson, going by the looks on their faces. Not that she could blame them. If Jim had come back for them, then the game was most likely over.

"You can't be allowed to continue. You just can't. I would try to convince you , but everything I have to say has already crossed your mind."

Disappointment coursed through Mary's body. She had so been looking forward to playing with these two idiots. But Jim was the boss, and for some reason he had decided that they couldn't go on breathing.

_Does he feel like Holmes will be his undoing?_

Holmes, facing Mary and all the snipers, looked down at Watson. Watson looked at him for a second, and then minutely nodded his head.

Even amidst her annoyance at Jim and disappointment at the loss of new playthings, she had to respect Watson's courage for whatever he had just agreed to.

"Probably my answer has crossed yours," Holmes said, as he turned around towards Jim. Holmes aimed the gun at Jim, and Mary aimed her rifle at Holmes. Then, slowly, Holmes lowered the gun to the vest that was still laying on the ground between the two men.

Mary went cold as she tightened her grip on her rifle.

_Well, well. Holmes has a pair of bollocks on him, after all. I might be starting to see what Jim sees in this one._

Just as Mary was starting to wonder if she should go ahead and take out Holmes, Jim's phone started ringing. The upbeat music echoed eerily off the tiled walls. Jim stood there, statuesquely, as Watson and Holmes looked at each other, confused.

Finally, Jim's face fell into one of annoyance as he asked if Holmes minded that he answered the call. Mary smiled to herself, both out of relief that the tension was broken and out of pleasure at Jim's humor.

The look of annoyance deepened slightly as Jim pulled his phone out of his pocket and looked at the screen before answering. Even in his annoyance though, he was still polite and flirty with Holmes, mouthing sorry to him.

Jim turned his back to everyone, then screamed "Say that again!" Everyone in the room jumped, including her highly trained snipers. The only two people to remain calm were herself and Watson.

_Interesting. This little soldier never ceases to surprise me._

"Say that again, and know that if you are lying to me, I will find you and I will skin you."

_Well, shit. _Whoever was on the phone was now in a dangerous position. They obviously had something that Jim would want, but they had better actual have it, or they were dead. Jim did not play around with people, and he did not like not getting what he wanted.

Jim lowered the phone, his face full of… something. She'd never really seen that look on Jim's face before. It was a mix of confusion, and maybe … disappointment? He walked towards Holmes, stopping in front of the vest.

"Sorry, wrong day to die."

"Did you get a better offer?"

Jim looked down at his phone, then back up at Holmes, looking more like he normally did. "You'll be hearing from me, Sherlock."

Jim then turned, putting the phone back to his ear as he walked out of the pool the same way he had originally come in. Just before he got to the door, he raised his hand and snapped, signaling them all to stand down.

Mary and her team turned off their rifle lasers, but Mary still kept a watchful eye on the two men below her.

"What happened there?" Watson asked.

"Someone changed his mind. The question is, who?"

_Who indeed._

Mary's thoughts were racing, trying to figure out who the phone call was from and what had just happened. Curiosity was burning through her. And what had Jim meant when he said "Wrong day to die?" She knew that he got bored with the world, never felt like he had had anyone who was an equal in it, and so therefore could get very depressed, but she had no clue until this moment that he was possibly suicidal.

Mary watched as the two men collected themselves and then left the building. Even though she knew she needed to get to Jim and find out what all of _that_ was about, she took a minute to ponder Holmes and Watson – the genius and his pet. There was no denying that they ended up being far more fascinating than she had originally thought. And their unknown love for each other, oh that really would be so much fun to play with.

Mary packed up her sniper rifle, then told her team that they were done for the day and worked out payments for everyone. As she left the pool to drive to Jim's, she looked forward to brainstorming with Jim all kinds of fun mind games and plots to mess with these two deliciously stupid, yet interesting, men. It would be fun to watch them dance, then stumble and fall. Because fall they will. There was no way to escape that, once Jim Moriarty decided to play with you.

* * *

Jim had plans for everything, every eventuality, and as much as she hated having to do it without him, Mary followed out his orders perfectly after his death. But when she got wind that Sherlock Holmes was still alive a year and a half after Jim blew his brains out on top of St. Bart's and Holmes was supposed to have plummeted to his death, Mary gleefully looked forward to the plan she was about to set in motion: become Mary Morstan, seduce John Watson and get cozy with him in order to lure Sherlock Holmes out of hiding. Not only would she be able to play with those deliciously stupid men again, but she would also be able to get her revenge on Sherlock Holmes for taking her genius away from her.

As she maneuvered herself into position to burn the heart out of Sherlock Holmes, all she could think was:

_Oh this is going to be fun._

* * *

**A/N -**

This is my first dive off the deep end into writing fanfic, so any criticisms would be greatly appreciated. Just be gentle with me.

The idea "What if Mary is Moran and had been at the pool that night?" came to me suddenly one night, and the story almost started writing itself. I'm not going to lie- it was hard work, especially writing about a canon scene. I hope it didn't get too boring for everyone, since I'm sure we all know that scene so well.

Super special thanks goes out to **Madi** for helping me figure out a way of making it clear that Mary is Moran in this story.

I would like to thank ivyblossom, wsswatson, and ifyouhaveenoughnerve on Tumblr for their excellent metas on Mary Morstan and how she is probably Moran. They greatly helped me wrap my head around Mary the psychopathic killer.

I would also like to thank **Arianne DeVere** for the use of her excellent transcripts, which were oh so helpful while writing this scene.

Most importantly, I would like to thank all of my friends who encouraged me to keep writing this story. I dedicate this to you all!

**Disclaimer:** I sadly do not own these characters.


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